A $ 2 billion dollar collaboration between farmers, conservationists and governments aims to repair the largest flowing freshwater system on Earth.

It's early in October when David Myerholtz climbs into the cab of his 18-ton combine to begin the long task of harvesting 1,500 acres of corn and soybeans he and his father grow every year around the village of Rollersville, Ohio. The powerful machine chews through 12 rows of corn at a time, leaving a wake of dry stalks, cobs and husks, while filling the combine’s hopper with golden kernels at a rate of a couple thousand bushels per hour. Beyond, a flat, brown patchwork of cropland stretches to the horizon.

One hundred fifty years ago, this was the middle of the Great Black Swamp, a wetland the size of Rhode Island. Today, one clue to that pre-agrarian era is a 10-foot-wide ditch, a relic of early Ohioans’ project to transform that impenetrable morass into some of the most fertile soil in North America. Beneath the fields, clay-lined channels originally dug by homesteaders carry excess water—often laden with fertilizer runoff—into thousands of miles of ditches, which pour into a dense network of streams and meandering rivers that flow out to the warm, shallow waters of Lake Erie.

In 2011, spurred by a warming climate and fed by phosphorus runoff from fertilizer, blue-green algae bloomed over a record-breaking 1,920 square miles of the lake’s surface. For three days in August 2014, Toledo was forced to shut off its water system—toxic algae had poisoned the drinking water for half a million people. The algae has returned each summer since then, threatening the lake’s plants and animals. Farmers upstream once rarely considered Lake Erie or any of the other Great Lakes in their day-to-day decision-making, but as humans begin to recognize their role in the Great Lakes ecosystem, the algae blooms have made fertilizer use part of a larger conversation.

Nitrogen runoff from farms and other sources is just one of the challenges that the Great Lakes—east to west, they are Ontario, Erie, Huron, Michigan and Superior—have faced along with increased human use over the past two centuries. Habitat loss from shoreline development has hurt migratory bird species. Overfishing and invasive aquatic plants and animals, brought in by shipping, have gobbled up or out competed native species and strained the food web. Dams have cut off access to upstream spawning grounds.

Today, people who depend on and care about the lakes are beginning to realize that their actions can make a positive difference. And now there is big money to back them up—since 2010, the Great Lakes Restoration Initiative, administered by the Environmental Protection Agency and other federal agencies, has distributed more than $2 billion to conservation groups and government entities to clean up and restore the lakes. Partners include The Nature Conservancy, which at the same time adopted a big-picture approach of its own to work on some of the lakes’ most serious problems, taking first steps to undo the damage and launching pilot programs that may serve as models for the rest of the basin.

“We’re trying to shape a better future for this massive ecosystem and all the people who depend upon it,” says Michael Reuter, director of the Conservancy’s Midwest Division, who hopes that a few decades’ hard work influencing policy and practices will pay off in the form of cleaner water and greater natural diversity and abundance. “We want to give the people who use and live in this basin the tools to manage their lands and waters in a much more sustainable way.”

The importance of those resources is hard to overstate. The Great Lakes, which together account for nearly a fifth of the Earth’s liquid surface fresh water, provide drinking water for 40 million people. They border eight states and one Canadian province, are directly connected to 1.5 million jobs and contribute $62 billion in wages to the U.S. economy. Many industries grew up along their shores, and today some 125 million tons of cargo are carried on the Great Lakes every year. Their fate lies in countless hands, from government agencies and corporate shipping concerns to recreational fishermen and family farmers like Myerholtz.

“I would love all Americans to understand the Great Lakes are a foremost economic engine and an incomparable natural resource that benefits the entire country,” Reuter says, emphasizing that this is one of the largest freshwater systems in the world. “People may not see them, drink their water or know their names—but these lakes touch and enrich their lives every day.”

European immigrants began settling on the shores of Lake Erie and Lake Ontario in the 18th century, but when the Erie Canal connected Lake Erie with the Hudson River in 1825, it kicked off an era of rapid expansion. Settlers poured into Ohio, and would-be farmers spent some 70 years installing ditches, drains and pumps to dry out the Great Black Swamp. Timber operations made quick work of Michigan’s old-growth forests, which by 1900 were logged into almost complete oblivion. Cities and industry expanded, pouring sewage and pollution into the lakes and the rivers that fed them. Pollution in tributaries and ports got so bad that the water in Ohio’s Cuyahoga River repeatedly caught fire.

Pollution diminished after the United States passed the Clean Water Act in 1972, but meanwhile, the lakes faced another insidious threat to the region: invasive species. Booming businesses in port cities like Duluth and Chicago brought seagoing ships, which often carried plants, fish, invertebrates and other species from far away in their ballast water. In the 1800s, the first wave of carp was introduced from Europe. Then sea lamprey showed up, and by 1946 had spread through all five Great Lakes, kicking off a cycle of invasions that would devastate many native species.

Invasive species don’t always look sinister, but the sea lamprey is another story. Its suction-cup mouth is lined with razor-like teeth, which it uses to latch onto the flanks of other fish. In the Great Lakes, lamprey kill large native fish like lake trout, lake sturgeon and walleye. Within 20 years, the invaders—with help from pollution and overfishing—had drastically reduced commercial catches.

By the 1960s, American and Canadian programs to control lamprey in the rivers where they spawn were succeeding, although their continued effectiveness comes at a cost of more than $20 million a year. But then came alewife, a small herring native to the Atlantic coast. With native predators wiped out by lamprey, the alewife population repeatedly exploded and crashed, in massive die-offs that fouled shores and beaches.

“Essentially what we’ve done with all these invasives is we’ve simplified the food web, so if there’s a change that impacts some of these species, it can crash the system,” says zoologist Lindsay Chadderton, who leads TNC’s efforts to combat invasives in the Great Lakes.

Restoring the natural complexity of the Great Lakes’ food web is a puzzle that local communities, states, the federal government, scientists and conservationists have been work-ing on for years. “We’re not expecting instant gratification,” Reuter says. “But over the next several decades we’d like to return to a healthier, more native fishery that does not need as much intensive management.”

Still, sometimes a simple strategy can make a big splash. That’s how Conservancy aquatic ecologist Matt Herbert found himself beside a barge in Lake Michigan two summers ago, supervising a hydraulic excavator as it shoveled 450 tons of limestone into Grand Traverse Bay.

The massive operation, a collaboration between TNC, the Michigan Department of Natural Resources and Central Michigan University, was aimed at a rather small fish: the cisco, popularly known as lake herring. A century ago, cisco were one of the most important commercial fi sh in the Great Lakes. Their numbers are still strong in Lake Superior, but they exist as remnant populations in Lakes Erie, Huron, Michigan and Ontario. In Grand Traverse Bay, near the top of Michigan’s Lower Peninsula, cisco lay their eggs in late autumn on rocky reefs, which provide shelter over the winter before the young hatch during spring, but a recent survey revealed that the remaining cisco depend on just two healthy reefs. A third reef had potential—if only it could be made a little bigger.

Augmenting the reef was only one part of the project, because cisco eggs also need protection from two aggressive invaders: round goby, a bottom-dwelling fi sh native to the Black and Caspian seas, and rusty crayfi sh, a crustacean introduced into the Great Lakes by bait fi shermen. The team settled on a method that uses electricity to kill the invaders on a reef just before native fi sh arrive to spawn. Herbert cautions that it will take fi ve years before the team can declare success. A heartier cisco population is one step toward a restored food web, and if this strategy works, it may serve as a model for eff orts elsewhere in the Great Lakes. And early data on the reef show native lake trout eggs in densities among the highest ever recorded, leaving Herbert and his colleagues buoyant about the future.

“We’re not going to be able to impact the population of gobies,” Herbert says. But “there’s room for cisco [and trout] to expand, and it looks like good things are happening.”

Good things are also happening in northwest Ohio, where in addition to harvest, early October means shorebird and waterfowl migration. Two and a half miles from the sandy shore of Lake Erie, a former cornfi eld known as the Blausey Unit swarms with bustling, squawking ducks, dowitchers, grebes and herons. A family of trumpeter swans—a species that was once nearly extinct in the lower 48 states—swim placidly through a pond, past a great egret perched on a muskrat house. A young bald eagle watches the scene from the top of a cottonwood tree.

The Blausey Unit is an outpost of the Ottawa National Wildlife Refuge, a wetland on the shore of Lake Erie managed by the U.S. Fish and Wildlife Service (FWS). The parcel was acquired from a local farming family in 1999. In 2012, with a 1.3 million grant through the Great Lakes Restoration Initiative and assistance from TNC, the agency set about undoing century-old subsurface drainage and restoring the land’s natural hydrology.

“We know we’ve lost 95 percent of our wetlands in this area,” says Amy Brennan, the Conservancy’s Lake Erie conservation director, standing on a dike at the property’s edge. “We’re not going to re-create the Great Black Swamp. No one’s deluding themselves about that.”

But she says TNC and FWS aim to restore as much wetland as they can, because in addition to their importance as habitat, these marshes serve as the lake’s kidneys. If enough wetland can be reconnected to Erie and its tributaries, it will filter out agricultural runoff before it reaches the lake, reducing the frequency and severity of the algal blooms that damage the aquatic ecosystem and foul the drinking water.

When people began draining the wetlands, water flows started changing. Today, intense winter, spring and summer rains run off the fields, carrying nutrients and sediments with them. And dealing with the implications of drainage means working with the agricultural industry.

Nutrient runoff has been a global problem since synthetic fertilizer was developed in the early 20th century and industrial agriculture intensified after World War II. Fertilizer costs money, and agriculture is a business with tight profit margins, but in the past it was hard to know how much fertilizer was enough—and since excess doesn’t hurt crop yields, it can seem riskier to use too little.

Technology, however, may offer a partial solution. New methods of soil testing allow farmers to learn precisely how much fertilizer their fields need and where extra nutrients will have the most impact. Coupled with new approaches to application—like strip tilling, in which fertilizer is incorporated into the soil several inches underground—this technology has the dual benefit of reducing runoff and helping the farmer’s bottom line.

The challenge lies in persuading farmers to upgrade their equipment and invest in high-tech crop advising, and the best evangelists are farmers and the crop advisers they trust. And that’s where David Myerholtz comes in. Like most of his neighbors, Myerholtz works with The Andersons, a company that provides fertilizer to Ohio farmers. In 2016, his local branch was certified through a voluntary program referred to as 4Rs Nutrient Stewardship (“4Rs” is shorthand for “the right source of nutrients at the right rate and right time in the right place”), which helps farmers use fertilizer more strategically and apply it to fields in a way that minimizes erosion and runoff. The 44 providers that have earned the certification to date influence some 2.76 million acres of farms, including about 40 percent of the acreage in the Western Lake Erie Basin. Carrie Vollmer-Sanders, who manages nutrient strategy for TNC’s North America Agriculture Program, helped develop the 4Rs, and she uses them on her own family farm in northwest Ohio.

“My hope,” she says, “is that within 10 to 15 years, harmful algal blooms will be a thing of the past.”

While TNC and its partners are making progress, a new threat to the Great Lakes recently emerged in the form of budget cuts proposed by President Donald Trump’s administration. In a budget proposal released this past March, the White House wanted to eliminate funding for the Great Lakes Restoration Initiative and slash the EPA’s overall budget by nearly a third.

It was a stunning blow, but once again, Reuter says there is reason to be hopeful. The proposed cuts have been met with bipartisan opposition, as Republican and Democratic elected officials from across the Great Lakes region have rallied to protect restoration funding.

“I’m encouraged,” he says, noting that Congress, not the executive branch, will ultimately make decisions about the budget for federal environmental initiatives. “There is an irrepressible affinity with the Great Lakes, by people within the basin, from New York to Minnesota. These people are recognizing what is at stake here—culturally, socially, environmentally and economically. Sixty or 70 years ago, there were a lot of abuses, and people don’t want to see those happen again. They do not want to see the Cuyahoga River catch fire again. That is a not-too-distant memory.”

The halls of Congress and the burning Cuyahoga might feel far off from Myerholtz’s cornfield, but up in the cab of his combine, he has time to ruminate on the interconnectedness of humans and nature. While crop yield, return on investment and the often-uncertain economics are never far from his mind, he also worries about his impact on Lake Erie.

“It’s one of those things where you really start thinking about your footprint,” he says. At 50, Myerholtz has seen the Great Lakes’ fortunes rise and fall, and he has watched human priorities shift as our understanding of the lakes’ importance—and fragility—grows.

“When you’ve lived here all your life, you see the water run into the ditch,” he says. “You know where it goes. Who wants to admit to any responsibility? But I think we all want to be part of the solution.”

Amy Crawford is a freelance writer based in Michigan. She has also written for Smithsonian magazine, The Boston Globe and CityLab.

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